Highly selective separation of propylene/propane mixture on cost-effectively four-carbon linkers based metal-organic frameworks

The separation of propylene and propane is an important but challenging process,primarily achieved through energy-intensive distillation technology in the petrochemical industry.Here,we reported two natural C4linkers based metal–organic frameworks(MIP-202 and MIP-203)for C_(3)H_(6)/C_(3)H_(8)separation.Adsorption isotherms and selectivity calculations were performed to study the adsorption performance for C_(3)H_(6)/C_(3)H_(8)separation.Results show that C_(3)H_(6)/C_(3)H_(8)uptake ratios(298 K,100 kPa)for MIP-202 and MIP-203 are 2.34 and 7.4,respectively.C_(3)H_(6)/C_(3)H_(8)uptake ratio(303 K,100 k Pa)for MIP-203 is up to50.0.The mechanism for enhanced separation performance of C_(3)H_(6)/C_(3)H_(8)on MIP-203 at higher temperature(303 K)was revealed by the in situ PXRD characterization.The adsorption selectivities of C_(3)H_(6)/C_(3)H_(8)on MIP-202 and MIP-203(298 K,100 k Pa)are 8.8 and 551.4,respectively.The mechanism for the preferential adsorption of C_(3)H_(6)over C_(3)H_(8)in MIP-202 and MIP-203 was revealed by the Monte Carlo simulation.The cost of organic ligands for MIP-202 and MIP-203 was lower than that of organic ligands for those top-performance MOFs.Our work sets a new benchmark for C_(3)H_(6)sorbents with high adsorption selectivities.

Jinan University Achieves Breakthrough in Propylene/Propane Separation

Recently,the research team at the Jinan University(JNU)based on the adsorption/desorption technology over metal-organic frameworks(MOF)for the first time proposes an orthogonal array dynamic screening mechanism to successfully construct the separation mechanism-based frame material(JNU-3),which can be used in adsorptive separation of propylene from propane.MOF is a kind of crystalline porous materials with a definite composition and structure formed by self-assembled metal nodes and organic ligands.

Catalytic Reaction Kinetics of Propylene Dimerization to 4-Methyl-1-Pentene Using Cu-K/K_(2)CO_(3) Solid Base Catalyst

The catalysis technology of propylene dimerization to form 4-methyl-1-pentene(4MP1)using a Cu-K/K_(2)CO_(3) solid base catalyst is a well-known heterogeneous catalytic reaction.In this study,the intrinsic kinetics of propylene dimerization were studied in a fixed-bed continuous reactor.Internal and external diffusion during the dimerization reaction experiments were eliminated by adjusting the flow rate of the carrier gas and the particle size of the catalyst support.Then,the concentration changes of each substance at the outlet of the catalyst bed under different residence times were investigated.Moreover,the suitable reaction kinetics equations was derived using the Langmuir Hinshelwood-Hougen-Watson kinetic model.Finally,the activation energy for each reaction involved in the dimerization reaction was calculated.The activation energies of 4MP1,branched by-products,and 1-hexene were 115.0,150.8,and 177.4 kJ/mol,respectively.The effect of process conditions on propylene dimerization with solid base catalysts was studied through kinetic model simulation.By comparing the theoretical values obtained from the simulation with the experimental results,the applicability and accuracy of the kinetic model were verified.

Facile Surface Engineering of NiCo_(2)O_(4) to Boost Propane Oxidation Activity

Spinel oxide(NiCo_(2)O_(4))has demonstrated great potential to replace noble metal catalysts for the oxidation reaction of air pollutants.To further boost the oxidation ability of such catalysts,in this study,a facile surface-engineering strategy wherein NiCo_(2)O_(4) was treated with different alkali solvents was developed.The obtained catalyst(NiCo_(2)O_(4)-OH)showed a higher surface alkalinity and more surface defects compared to the pristine spinel oxide,including enhanced structural distortion as well as promoted oxygen vacancies.The propane oxidation ability of NiCo_(2)O_(4)-OH was greatly enhanced,with a propane conversion rate that was approximately 6.4 times higher than that of pristine NiCo_(2)O_(4) at a reaction temperature 193℃.This work sets a valuable paradigm for the surface modulation of spinel oxide via alkali treatment to ensure a high-performance oxidation catalyst.

Synthesis of propylene carbonate from urea and 1,2-propanediol

The production of propylene carbonate （PC） from urea and 1,2-propanediol （PG） was investigated in a batch process. The catalytic performances of zinc chloride and magnesium chloride were investigated for this reaction system. The influences of various operation conditions on the PC yield were explored. In this work, MgCl2 and ZnCl2 showed the excellent catalytic activity toward PC synthesis, and the yields of propylene carbonate reached 96.5% and 92.4%, respectively. The optimum reaction conditions were as follows： ethanol/urea molar ratio of 4, catalyst concentration of 1.5%, reaction temperature of 160 ℃, reaction time of 3 h, respectively. The route from urea and 1,2-propanediol shows advantages, such as mild reaction condition and safe operation. The catalytic system is environmentally benign.

Effect of Sr loading on oxydehydrogenation of propane to propylene over Al_2O_3-supported V-Mo catalysts

Incorporation of strontium into V-Mo alumina-supported catalyst enhanced its performance (increased conversion and selectivity,decreased reducibility and improved stability) in propane oxydehydrogenation to propylene.12.5% Sr loading was shown to be the optimum content to the V-Mo catalyst.The results were supported by various characterization techniques,namely,BET,XRD,SEM,FTIR and TPD.

A high propylene productivity over B2O3/SiO2@honeycomb cordierite catalyst for oxidative dehydrogenation of propane

Boron-based metal-free catalysts for oxidative dehydrogenation of propane(ODHP)have drawn great attention in both academia and industry due to their impressive activity and olefin selectivity.Herein,the SiO2 and B2O3 sequentially coated honeycomb cordierite catalyst is designed by a two-step wash-coat method with different B2O3 loadings(0.1%–10%)and calcination temperatures(600,700,800℃).SiO2 obtained by TEOS hydrolysis acts as a media layer to bridge the cordierite substrate and boron oxide via abundant Si\\OH groups.The welldeveloped straight channels of honeycomb cordierite make it possible to carry out the reactor under high gas hourly space velocity(GHSV)and the thin wash-coated B2O3 layer can effectively facilitate the pore diffusion on the catalyst.The prepared B2O3/SiO2@HC monolithic catalyst exhibits good catalytic performance at low boron oxide loading and achieves excellent propylene selectivity(86.0%),olefin selectivity(97.6%,propylene and ethylene)and negligible CO2(0.1%)at 16.9%propane conversion under high GHSV of 345,600 ml·(g B2O3)^-1·h^-1,leading to a high propylene space time yield of 15.7 g C3H6·(g B2O3)^-1·h^-1 by suppressing the overoxidation.The obtained results strongly indicate that the boron-based monolithic catalyst can be properly fabricated to warrant the high activity and high throughput with its high gas/surface ratio and straight channels.

TiO₂Films Synthesis over Polypropylene by Sol-Gel Assisted with Hydrothermal Treatment for the Photocatalytic Propane Degradation

The present investigation shows experimental results obtained with TiO2 thin films synthesized by the sol-gel method assisted with hydrothermal treatment over polypropylene, using the dip coating technique. Obtained coatings were characterized through SEM, XRD, UV-Vis and the photo- catalytic activity was monitored by GC. According to results, the hydrothermal treatment facilitates the crystallization of the TiO2 anatase phase, which is present in all synthesized films. Crystal size formed from precursor solutions (estimated by the Scherrer’s equation) depends on the time and temperature of the hydrothermal treatment, wherein solution exposed to a higher temperature treatment of 150。C for 1.5 h (H150/1.5) exhibited a larger crystal size compared to those synthesized at 80。C for 1.5 h and 3 h (H80/1.5 and H80/3). Sample H150/1.5 over polypropylene resulted in a uniform and crack free coating. This behavior was attributed to the precursor solution being denser than those synthesized at 80。C. Additionally, the photocatalytic activity of the coatings was evaluated through the degradation of propane. Coating H150/1.5 reached 100% conversion after 3 h of UV light irradiation.

Influence of carbonization temperature on cobalt-based nitrogendoped carbon nanopolyhedra derived from ZIF-67 for nonoxidative propane dehydrogenation

Propylene is a significant basic material for petrochemicals such as polypropylene,propylene oxide,etc.With abundant propane supply from shale gas,propane dehydrogenation(PDH)becomes extensively attractive as an on-purpose propylene production route in recent years.Nitrogen-doped carbon(NC)nanopolyhedra supported cobalt catalysts were synthesized in one-step of ZIF-67 pyrolysis and investigated further in PDH.XPS,TEM and N_(2) adsorption-desorption were used to study the influence of carbonization temperature on as-prepared NC supported cobalt catalysts.The temperature is found to affect the cobalt phase and nitrogen species of the catalysts.And the positive correlation was established between Co0 proportion and space time yield of propylene,indicating that the modulation of carbonization temperature could be important for catalytic performance.

A mini review on oxidative dehydrogenation of propane over boron nitride catalysts

Oxidative dehydrogenation of propane is an attractive route for the synthesis of propylene due to its favorable thermodynamic and kinetic characteristics, however, it is challenging to realize high selectivity towards propylene. Recently, it has been discovered that boron nitride (BN) is a promising catalyst that affords superior selectivity towards propylene in oxidative dehydrogenation of propane. Summarizing the progress and unravelling the reaction mechanism of BN in oxidative dehydrogenation of propane are of great significance for the rational design of efficient catalysts in the future. Herein, in this review, the underlying reaction mechanisms of oxidative dehydrogenation of propane over BN are extracted;the developed BN catalysts are classified into pristine BN, functionalized BN, supported BN and others, and the applications of each category of BN catalysts in oxidative dehydrogenation of propane are summarized;the challenges and opportunities on oxidative dehydrogenation of propane over BN are pointed out, aiming to inspire more studies and advance this research field.

Sub-nanometer Pt_(2)In_(3) intermetallics as ultra-stable catalyst for propane dehydrogenation

Pt-based catalysts are the typical industrial catalysts for propane dehydrogenation(PDH),which still suffer from insufficient lo ng-term durability due to the structu ral instability and coke deposition.A commercial γ-Al_(2)O_(3) supported thermally robust sub-nanometer Pt2In3intermetallic catalyst with atomically ordered structure and rigorously separated Pt single atoms was fabricated,which showed outstanding robustness in 240 h long-term operation at 600℃ with the deactivation rate constant kdas low as0.00078 h^(-1), ranking among the lowest reported values.Based on various in situ characterizations and theoretical calculations,it was proved that the catalyst stability not only resulted from the separated Pt single-atom sites but also significantly affected by the distance of adjacent Pt atoms.An increasing distance to 3.25 A in the Pt_(2)In_(3)could induce a weak π-adsorption configuration of propylene on Pt sites,which facilitated the desorption of propylene and restrained the side reactions like coking.

Effect of boron species on carbon surface on oxidative dehydrogenation of propane

Carbon catalysts for propane oxidative dehydrogenation(PODH)can potentially replace metal oxide catalysts due to their environmental friendliness(greenness)and excellent catalytic performance.Biomass carbon materials have the advantages of being abundant in variety,inexpensive,and easily available,but their catalytic selectivity is relatively poor in PODH.Therefore,we report here on a boron-doped sisal fiber carbon catalyst,which showed excellent selectivity of propylene in PODH,excluding the effect of surface-covered B2O3 on the catalytic performance by hot water washing.The carbon material exhibited the best catalytic performance with a load of 2%(mass)and a calcination temperature of 1100℃.At a reaction temperature of 400℃,the conversion rate of propane was 2.0%,and the selectivity toward propylene reached 88.6%.The new chemical bonds formed by boron on the surface of the carbon materials had an important effect on the catalytic performance,as determined by XPS characterization.The BAO groups affected the catalytic activity by inhibiting the generation of electrophilic oxygen species,while the BAC content improved the selectivity toward propylene by changing the electron cloud density.

Finned Zn-MFI zeolite encapsulated noble metal nanoparticle catalysts for the oxidative dehydrogenation of propane with carbon dioxide

Oxidative dehydrogenation of propane with carbon dioxide(CO_(2)-ODP)characterizes the tandem dehydrogenation of propane to propylene with the reduction of the greenhouse gas of CO_(2)to valuable CO.However,the existing catalyst is limited due to the poor activity and stability,which hinders its industrialization.Herein,we design the finned Zn-MFI zeolite encapsulated noble metal nanoparticles(NPs)as bifunctional catalysts(NPs@Zn-MFI)for CO_(2)-ODP.Characterization results reveal that the Zn2+species are coordinated with the MFI zeolite matrix as isolated cations and the NPs of Pt,Rh,or Rh Pt are highly dispersed in the zeolite crystals.The isolated Zn2+cations are very effective for activating the propane and the small NPs are favorable for activating the CO_(2),which synergistically promote the selective transformation of propane and CO_(2)to propylene and CO.As a result,the optimal 0.25%Rh0.50%Pt@Zn-MFI catalyst shows the best propylene yield,satisfactory CO_(2)conversion,and long-term stability.Moreover,considering the tunable synergetic effects between the isolated cations and NPs,the developed approach offers a general guideline to design more efficient CO_(2)-ODP catalysts,which is validated by the improved performance of the bifunctional catalysts via simply substituting Sn4+cations for Zn2+cations in the MFI zeolite matrix.

Stability and Thermal Property Optimization of Propylene Glycol-Based MWCNT Nanofluids

Propylene glycol-based MWCNT(multi-walled carbon nanotubes)nanofluids were prepared in the framework of a two-step method and by using a suitable PVP(polyvinyl pyrrolidone)dispersant.The BBD(Box-Behnken design)model was exploited to analyze 17 sets of experiments and examine the sensitivity of the absorbance to three parameters,namely the concentration of MWCNT,the SN ratio(mass ratio of carbon nanotubes to sur-factants)and the sonication time.The results have revealed that,while the SN ratio and concentration of MWCNT have a strong effect on the absorbance,the influence of the sonication time is less important.The sta-tistical method of analysis of variance(ANOVA)was further used to determine the F-and p-values of the model.Five experiments were run to validate this approach.Since sample 2 was found to display the greatest absorbance,it was selected for stability monitoring as well as thermal conductivity and viscosity measurements.This sample has been found to be stable;the viscosity decreased with increasing temperature;the addition of MWCNT nano-particles was more effective in improving the thermal conductivity of propylene glycol than other methods in the literature.Moreover,the MWCNT nanofluid based on propylene glycol exhibited higher thermal conductivity at low temperatures.

Manipulating Zn^(2+)solvation environment in poly(propylene glycol)-based aqueous Li^(+)/Zn^(2+)electrolytes for high-voltage hybrid ion batteries

Compared with aqueous single-ion batteries,rechargeable aqueous hybrid ion batteries,especially Li^(+)/Zn^(2+)hybrid ion batteries,are receiving extensive interest owing to their low cost,high operating voltage,and energy density.However,their working voltage and lifespan are limited by the decomposition of water and the growth of Zn dendrites.Herein,detrimental side reactions induced by the water reduction and the Zn dendrite growth are successfully suppressed by a poly(propylene glycol)(PPG)-based hybrid ion electrolyte[(1 m Zn(TFSI)2+10 m LiTFSI)in PPG/H2O].The addition of PPG in the electrolyte can not only enhance the bonding strength of hydrogen-bond in water but also tailor the solvation sheath of Zn2+as revealed by synchrotron X-rays.The participated solvation of PPG with Zn^(2+)can weaken Zn-H_(2)O interactions and redistribute Zn^(2+)flux on the surface of the Zn anode,thus inducing favorably even deposition of Zn.In addition,the decomposition of TFSI-contributes a ZnF_(2)-enriched solid electrolyte interface at the Zn anode to further prevent water decomposition and restrain Zn dendrites.The PPG-based electrolyte enables 2.1 V LiMnO_(2)//Zn batteries to deliver high specific capacities(121.7 mAh g^(-1)for a coin cell and 90 mAh g^(-1)for a pouch cell),and maintain 80%of the capacity over 700 cycles at 0.5 C,suggesting a promising pathway for highly reversible aqueous hybrid ion batteries.

Measurement and Correlation of Solubility for Propylene in 2-Propanol-Water Solutions

In order to obtain the solubility data of propylene in 2-propanol-water solutions, gas-liquid equilibrium (GLE) experiments were carried out at 303.15-333.15 K, 0.27-0.98 MPa in a static equilibrium still. The original mass ratio of 2-propanol to water was 9∶1,8∶2,7∶3,1∶0, respectively. The equilibrium data were correlated with an empirical model and the regression of model parameters was completed by Gauss-Newton nonlinear least square (NLS). The average relative deviation (ARD) between the experimental and calculated value is 1.570 0, and the maximum relative deviation (MRD) is 4.820 0. In addition, a simple approach that correlated the model parameters with the system composition was also provided.

有机-无机杂化材料[Ag(bpp)]_2(tdc)·8H_2O的合成,结构和光学性能(bpp=1,3-bis(4-pyridyl)propane,tdc=thiophene-2,5-dicarboxylate)(英文)

在室温下,AgNO3、1,3-二(4-吡啶基)丙烷和2,5-噻吩二甲酸在丙酮水溶液中反应,经数周后得到完整无色晶体[Ag(bpp)]2(tdc)·8H2O。该晶体由荷正电的类似正弦曲线形状的配位聚合物链,[Ag(bpp)]∞,和有机负离子tdc2-构成,其间分布着起重要作用的结晶水分子。相邻的阳离子链通过静电作用与tdc2-阴离子堆积构成晶体的三维骨架,结晶水分子分布其间并形成氢键,对晶体堆积起定位作用。[Ag(bpp)]2(tdc)·8H2O的晶体学数据:单斜晶系,空间群C2/c,a=3.5447nm,b=0.92003nm,c=2.4119nm,β=106.56°,V=7.546nm3和Z=8;残差因子R1=0.0463,wR2=0.1142。UV/Vis/NIR漫反射光谱法测定表明其具有很强的选择性光吸收特性。

Robust microporous metal-organic framework with high moisture tolerance for efficient separation of propylene from propane

Adsorptive separation of propylene(C_(3)H_(6))from propylene/propane(C_(3)H_(8))is desired to replace energy-intensive cryogenic distillation for its energy efficiency,economical viability,and environment friendship.In this work,we report a cupper-based robust microporous metal-organic framework,Cu-Hmpba,constructed by the hard soft acid-base principle using the bifunctional pyridylcarboxylate ligand featuring methyl group,for high-efficient separation of the propylene/propane mixture.Under the synergistic effect of the protective group and hard soft acid base principle,Cu-Hmpba possesses good solvents stability,especially water stability.Cu-Hmpba exhibits the adsorption capacity of C_(3)H_(6)with 2.10 mmol g^(-1)and good equimolar C_(3)H_(6)/C_(3)H_(8)selectivity with 2.24 at ambient conditions.The gas adsorption experiments,IAST selectivity calculations and theoretical calculations comprehensively support the selective adsorption toward C_(3)H_(6)among C_(3)H_(6)/C_(3)H_(8)mixture.Furthermore,it could maintain stable under moisture environment,suggesting its potential for the industrial separation of C_(3)H_(6)/C_(3)H_(8)mixture.The results of experiments and simulations demonstrate that the Cu-Hmpba would be a candidate adsorbent for the separation and purification of light hydrocarbons,and this work provides the insight of syn-thesizing stable MOF materials for separating high-value chemicals.

Effects of ammonium exchange and Si/Al ratio on the conversion of methanol to propylene over a novel and large partical size ZSM-5

One type of ZSM-5 zeolite with large partical size was prepared and characterized by XRD, SEM, N2 adsorption-desorption, XRF, Py-IR and NH3-TPD techniques. Effects of ammonium exchange and SiO2/Al2O3 molar ratios on the reaction of methanol to propylene （MTP） over Na-ZSM-5 and H-ZSM-5 zeolites have been studied in a fixed-bed flow reactor under the operating conditions of T = 500 °C, P = 1 atm, and WHSV = 6 h-1. Ammonium exchange led to a rapid decrease in Na content for Na-ZSM-5 zeolite. The reaction results indicated that Na-ZSM-5 and H-ZSM-5 with different SiO2/Al2O3 molar ratios all exhibited high activity for methanol conversion. Ammonium exchange and the decreased SiO2/Al2O3 molar ratio of ZSM-5 zeolite led to an increase both in strong acid sites and weak acid sites. Na-ZSM-5 with high SiO2/Al2O3 molar ratio was favorable for the formation of propylene. The highest propylene selectivity （45.9%） was obtained over Na-ZSM-5 zeolite catalyst with SiO2/Al2O3 molar ratio of 220.

Effect of cerium addition on catalytic performance of PtSnNa/ZSM-5 catalyst for propane dehydrogenation

The effect of cerium addition on the catalytic performance of propane dehydrogenation over PtSnNaIZSM-5 catalyst has been investigated by reaction tests and some physicochemical characterization such as XRD, BET, TEM, XPS, NH3-TPD, H2 chemisorption, TPR and TPO techniques. It has been found that with suitable amount of cerium addition, the platinum dispersion increased, while the carbon deposition tended to be eliminated easily. In these cases, the presence of cerium could not only realize the better distribution of metallic particles on the support, but also strengthen the interactions between Sn species and the support. Additionally, XPS spectra confirmed that more amounts of tin could exist in oxidized form, which was advantageous to the reaction. In our experiments, PtSnNaCe （1.1 wt%）/ZSM-5 catalyst exhibited the best catalytic performance. After running the reaction for 750 h, propane conversion was maintained higher than 30% with the corresponding selectivity to propylene of about 97%.